The invention relates to adjusting the eyepiece of a viewing device, such as binoculars.
Many types of viewing devices use eyepieces to provide a desirable eye relief for the user. Eye relief is the distance from the user""s eye to the lens (or more precisely, from the iris of the user""s eye to the lens surface closest to the eye). A user puts the eyepiece of a viewing device against an area around the eye in order to establish and maintain the optimal eye relief for that particular viewing device as determined by the manufacturer. Since the eye relief of the viewing device directly affects the field of view of the user, eyepieces are often adjustable by the user to change the eye relief and, accordingly, the desired field of view of the user.
For example, conventional binoculars may have an adjustable eyepiece positioned between each of the user""s eyes and the binocular body. Depending on the user""s preferences and the image that is being viewed, the adjustable eyepieces allow the user to change the field of view seen through the eyepieces. The adjustable eyepieces may be set in a particular position so that each of user""s eyes is close to the respective first lens in the binoculars, in which case, the binoculars may focus an image with a large field of view in the eyepieces. Then the user may adjust the eyepieces to slightly increase the eye relief between each of the user""s eyes and respective first lens in the binoculars. As the eye relief is increased, the outer border of the image is eliminated from the original view and the field of view provided by the binoculars is decreased. For example, the field of view may be intentionally decreased by the user to eliminate an unwanted light source from the outer border of the image while focusing on the desired object.
Eyepieces for binoculars have used a rotational motion provided by the user in order to adjust the eye relief. The adjustable eyepiece has a movable part that is threadably mounted to a fixed part of the eyepiece, or alternatively, a movable part that uses a helical cam pathway and a cam follower to translate the rotating motion provided by the user into the axial motion of the movable part. These prior art adjustable eyepieces are susceptible to unintentional rotation by the user and subsequent change to the field of view seen by the user. Also, viewing devices with more than one adjustable eyepiece, such as binoculars, frequently have eyepieces that are not similarly adjusted, so the user may be required to consciously verify the positions of the eyepieces before each use. For example, binoculars may have one adjustable piece adjusted to provide a small eye relief and the other eyepiece adjusted to provide a larger eye relief, so the user may be required to similarly align eyepieces for better viewing before the next use.
The invention provides an adjustable eyepiece for a viewing device with a plurality of locking, or secured, axial positions. The adjustable eyepiece of the invention inhibits unintentional motion due to actions of the user and allows the user to easily maintain parallel alignment of multiple eyepieces on a viewing device.
In one aspect of the invention, an eyepiece apparatus for a viewing device with adjustable eye relief comprises a diopter ring to be affixed to the view device so that the diopter ring is stationary with respect to a lens in the viewing device, and a cam sleeve slideably coupled with the diopter ring, the sleeve is axially adjustable relative to the diopter ring so that the eye relief is adjustable. The eyepiece apparatus also includes a cam system associated with the diopter ring and the cam sleeve that enables the sleeve to be secured in at least two axial positions that remain fixed in the presence of an axial force applied to the cam sleeve toward the diopter ring.
In another aspect, the invention provides a viewing device comprising binoculars having a body and at least two lenses for focusing an image to eyes of a user, and two adjustable eyepieces coupled with the body of the binoculars. Each eyepiece includes a diopter ring affixed to the body, a cam sleeve slideably coupled with the diopter ring, and a cam system associated with the diopter ring and the cam sleeve that enables the cam sleeve to be secured in two axial positions relative to the diopter ring. The invention further provides parallel alignment of the user""s eyes with respect to the body of the binoculars when the two eyepieces have cam sleeves that are locked in similar axial positions.
In a third aspect of the invention, an eyepiece apparatus for a viewing device comprises a diopter ring with at least one cam follower mounted to the diopter ring, a cam sleeve that is slideably coupled with the diopter ring and axially adjustable relative to the diopter ring such that the eye relief is adjustable, and at least one L-shaped cam pathway formed in the cam sleeve. The L-shaped cam pathways are similar in number to the cam followers such that one cam follower is positioned in each cam pathway to restrict the motion of the cam sleeve relative to the diopter ring. Each L-shaped cam pathway includes a first leg axially extending to a first end of the cam pathway, wherein the cam sleeve is secured in a first axial position when the cam follower abuts the first end of the cam pathway. Additionally, each L-shaped cam pathway includes a second leg tangentially extending to a second end of the cam pathway, wherein the cam sleeve is secured in a second axial position when the cam follower abuts the second end of the cam pathway.